During the drilling of hydrocarbon-producing wells, several layers of the Earth's crust are drilled in order to reach the depths where these oil and gas deposits are located; these extracts are several geological layers, which have different characteristics as far as rock composition, pressures, and temperatures go. To achieve this purpose, drilling fluids are used. The drilling of wells is performed in both terrestrial and maritime locations and the selection and design of the fluids must be carried out so as to avoid problems and operational risks, lower operating costs, shorten drilling time, and increase the production of hydrocarbons.
Formations of dolomitized and fractured carbonates of the Upper Jurassic Kimmieridgian-Thithonian, the carbonate breccia from the Lower Paleocene and Upper Cretaceous, and the carbonated sands of the Middle Eocene are found when drilling is conducted in the Ku Maloob Zapp and Cantarell Production Facilities fields. These types of rocks have a stratigraphic-structural trap. Similarly, the Cantarell, Sihil, EK-Balam, Kuil, Homol and Onel fields deposits consist of fractured limestones of vugular porosity from the Breccia-Paleocene-Upper Cretaceous age, at an average depth of 3600-4800 vertical meters, hindering its normal drilling during well construction at the breccia stage (BTPKS).
In this field, wells are traditionally built by means of a 36″ drill bit using sea water to a drilling depth of 210 meters deep (md). Next, a 30″ lining pipe (LP) is settled. The next stage uses a 17½″ drill bit with a “Bentonite” water-based fluid to 1000 md and a 13⅜″ LP is inserted. The next stage is drilled with 12¼″ drill bit and inverse emulsion (I.E.) mud with a density of 1.48-2.01 g/cc down to the Upper Paleocene layer (±/−4600 md) and LP is set between 100 to 150 md above the estimated depth for safety purposes and to avoid loss of total circulation, which would cause a series of operational problems at the beginning of the next stage, such as low rate of penetration (ROP), stuck pipes, etc. Drilling then proceeds using an 8½″ drill bit, forming an angle up to 30°, to 4800 md (4700 mv) in the Lower Cretaceous formation. In most cases a low-density (L.D) fluid of 0.92 g/cc is used with expected with total circulation loss (quantified cases of up to 23,000 m3 lost, diesel-based low-density fluid).
The application of a high performance aqueous-phase polymer fluid formed by the method of the present invention, for the fifth step or 6½″ step, due to the nature of the naturally-fractured deposit, is drilled with total circulation loss in maritime locations. To drill in these locations, oil- or water-based fluid systems are currently used, which require expensive logistics and the use of mud vessels to transport extensive contents of drilling water and diesel. For these wells, drilling operations are conducted pumping drilling fluid during 24 hours, and the water and diesel supplies are totally consumed, causing the interruption of drilling operations and the suspension of operations in drilling rigs more than 80 kilometers offshore due to insufficient water or diesel. The availability of supplies for fluid preparation and maintenance must be considered for the purpose of reducing transport costs and waiting times for the supply of such additives. Due to high operation costs generated daily by total circulation losses during breccia perforation (8½″ and 6½″ steps), as well as different operational problems, such as pipe entrapment and sticking because of the suspension of shears and clay instability, the selection of appropriate fluid systems for drilling operations is critical and requires a better and innovative design.
For well drilling in the Ku Maloob Zaap and Cantarell fields, the method and application of the high performance aqueous-phase polymer fluid technology were used in the breccia area, with high-performance polymer products, mainly liquid, easy and quick to mix, that guarantee the necessary technical parameters demanded, such as suspension capacity, the carrying of shears to the breccia zone, filtrate control, inhibition of the clay formations such as the lutitic collars of the Upper Jurassic, thermal stability, and resistance to contamination such as anhydrite and CO2, among others that delay the operations caused by the lack of fluid during the total circulation losses.
In the current market, there are companies that apply fluids; for example, the MI Company, which has a system called BAMIL to drill in loss zones, comprised of (3) liquid products and that in its preparation manages to obtain up to 35 seconds of viscosity with a 4:00 hour preparation time for every 70 m3, and inhibition limitations up to 18 CEC. The products have degradation and precipitation on the very low-lubricity liquid Xanthan Gum.
The QMAX Company has a system called QBAM, comprised of 8 chemical products, 5 of which are in powder form and 3 in liquid form, which significantly affects the time it takes for fluid preparation: 4:30 hours for every 70 m3. FIG. 5, presenting clots of polymer in the system and inhibition limitations up to 18 CEC.
Furthermore, the Global Drilling Fluids Company has a system comprising 8 products, 5 of which are in a powder form and 3 in a liquid form; a pre-treatment has to be applied to the seawater, and during preparation, clots are formed in the fluid, which must be stirred longer preparing in 4:50 minutes for every 70 m3, with inhibition of up to 20 CEC.
In current systems, the presence of Xanthan Gum clots when preparing the fluid directly affects their performance and that of the circulation system, since the clots, also called “fish eyes”, may cover the strainers of fluid pumps, drilling tubing, and down-hole drilling motors; therefore, it could be expected that the mix will be finished evenly, thus substantially increasing the fluid preparation times.
Some of the problems that most affect drilling with the use of these systems are the following:                a) High preparation time, causing an intermittent drilling.        b) Great volumes of raw materials, FIG. 1(A), causing pending suspension of materials.        c) insufficient inhibition in the system causing sticking of pipes.        d) Use of mud vessels, as support in the preparation and pumping.        e) Little progress in drilling due to low rheological properties (low viscosity).        f) Long drilling times.        
The method of this invention is intended to eliminate the current aforementioned problems, achieve a reduction in the volumes to be consumed as a consequence of the improvement in the times once the drilling parameters have been improved by providing a very similar lubricity to the oil-based fluids and cleaning of the well, with no need to prepare cleaning sweeps, eliminating the use of supporting vessels for fluid preparation and pumping, and developing a continuous drilling.
Currently, there is no system prepared with so few components and that complies with the speed, preparation, inhibition, and lubricity requirements. Considering that well drilling is an activity more than 60 years old and a system that manages to achieve this activity has not been presented. The stage of the well where these kinds of fluids are usually used is programmed for an average of 20 m per day when 120 m per day are drilled with this system.
One of the objectives of the invention is to provide a method to form an aqueous-phase polymer fluid with certain chemical components interacting in a stable way to overcome the current technical problems in well drilling.
Another objective of the invention is to provide a system to form an aqueous-phase polymer fluid with certain elements interacting to overcome the current technical problems in well drilling.